1. Technical Field
The present invention relates to an analysis method for a regional image, and more particularly, to an analysis method for a regional image applied to analysis of an image datum captured by a C-arm device.
2. Description of Related Art
In orthopedics surgery, for precisely locating the nidi, plural medical images are usually acquired prior to the surgery whereby orthopedists can diagnose the bone status and determine the surgery is for the purposes of repair and fixation or for replacing artificial implants, such as artificial joints.
In the case that bone repair involves implanting artificial implants, success of the surgery hinges on the locational precision of the artificial implants in human bodies. Since the repaired bones are intended to perform basic movements, any inaccuracy of the arrangement of the artificial implants can pose the patients in the risk of dislocation, increased joint abrasion, and even leg-length discrepancy.
Therefore, during the surgery, orthopedists have to repeatedly take the X-ray images of the nidi for confirming the locational precision of the artificial implants. However, while a large number of such X-ray images are acquired, the health of the present medical staff can be adversely affected by the radioactive rays coming along with X-ray photography.
By comparison, a surgical navigation system facilitates remedying the problem of taking a large number of X-ray images during surgery. Such a system acquires required images prior to the surgery so as to enable preplanning of the surgical path for the surgical instruments. Thereby, not only can the surgery be simplified and the medical staff be protected against the long-term radioactive-ray exposure, but also the accuracy of the surgery can be improved.
In order to achieve the highly strict requirement of pre-surgery planning accuracy, in addition to the high quality, clear images acquired prior to surgery, another critical point is how to define the correct related locations with the images. For this end, a C-arm device, which benefits for its high mobility and ability of rotation, is popular for taking X-ray images in orthopedics surgery. Such a C-arm device, in taking X-ray images, has to be used with a calibration device, which shows its steel ball image data in the images for facilitating accurately defining object locality in the images. However, images captured by the C-arm device tend to contain brighter or darker image signals that hinder optimization of the gray scale values throughout images, rendering each said steel ball image datum unrecognizable in the image data during a global analysis, and in turn causing the object locality in the pre-surgery images undeterminable.